Selective epitaxy process with alternating gas supply

Abstract

In one example, a method of epitaxially forming a silicon-containing material on a substrate surface is presented which includes positioning a substrate into a process chamber. The substrate has a monocrystalline surface and at least a second surface, such as an amorphous surface and/or a polycrystalline surface. The substrate is exposed to a deposition gas to deposit an epitaxial layer on the monocrystalline surface and a polycrystalline layer on the second surface. The deposition gas preferably contains a silicon source and at least a second elemental source, such as a germanium source, a carbon source and/or combinations thereof. Thereafter, the method further provides exposing the substrate to an etchant gas to etch the polycrystalline layer and the epitaxial layer in a manner such that the polycrystalline layer is etched at a faster rate than the epitaxial layer. The method may further include a deposition cycle that includes repeating the exposure of the substrate to the deposition and etchant gases to form a silicon-containing material with a predetermined thickness.

The invention claimed is: 
     
       1. A method for selectively and epitaxially forming a silicon-containing material on a substrate surface, comprising:
 positioning a substrate comprising a monocrystalline surface and at least a dielectric surface into a process chamber; and 
 performing a deposition sequence at least two times, the deposition sequence comprising:
 depositing an epitaxial material on the monocrystalline surface while simultaneously depositing a second material on the dielectric surface, the second material comprising a material selected from the group consisting of a polycrystalline material, an amorphous material, and combinations thereof; and subsequently 
 etching the second material, wherein the net result of the deposition sequence consists essentially of the epitaxial material selectively grown on the monocrystalline surface, wherein the epitaxial material comprises silicon-carbon. 
 
 
     
     
       2. A method for selectively and epitaxially forming a silicon-carbon-containing material on a substrate surface, comprising:
 positioning a substrate comprising a monocrystalline surface and at least a dielectric surface into a process chamber; and 
 performing a deposition sequence at least two times, the deposition sequence, comprising:
 depositing an epitaxial material on the monocrystalline surface while simultaneously depositing a second material on the dielectric surface, the second material comprising a material selected from the group consisting of a polycrystalline material, an amorphous material, and combinations thereof; and subsequently 
 etching the second material, wherein the net result of the deposition sequence consists essentially of the epitaxial material selectively grown on the monocrystalline surface, the epitaxial material having a graded carbon concentration. 
 
 
     
     
       3. The method of  claim 2 , wherein the deposition sequence is repeated until a predetermined thickness of the silicon-carbon-containing material is achieved. 
     
     
       4. The method of  claim 2 , wherein the second material is deposited to a thickness up to about an atomic layer in each sequence. 
     
     
       5. The method of  claim 2 , wherein the deposition sequence is conducted at a temperature within a range from about 500° C. to about 750° C. 
     
     
       6. The method of  claim 2 , wherein the etching comprises providing an etching gas comprising a compound selected from the group consisting of hydrogen chloride, chlorine gas, and combinations thereof. 
     
     
       7. A method for selectively and epitaxially forming a silicon-containing material on a substrate surface, comprising:
 positioning a substrate comprising a monocrystalline surface and at least a dielectric surface into a process chamber; and 
 performing a deposition sequence at least two times, the deposition sequence comprising:
 depositing a first epitaxial material on the monocrystalline surface while simultaneously depositing a second material on the dielectric surface, the second material comprising a material selected from the group consisting of a polycrystalline material, an amorphous material, and combinations thereof; 
 depositing a third epitaxial material on the first epitaxial material while simultaneously depositing a fourth material on the second material; and subsequently 
 etching the second and fourth materials, wherein the net result of the deposition sequence consists essentially of the first epitaxial material selectively grown on the monocrystalline surface and the third epitaxial material selectively grown on the first epitaxial material. 
 
 
     
     
       8. The method of  claim 7 , wherein the deposition sequence further comprises:
 purging after either deposition. 
 
     
     
       9. The method of  claim 7 , wherein the deposition sequence further comprises:
 purging after the etching. 
 
     
     
       10. The method of  claim 7 , wherein the deposition sequence is repeated until a predetermined thickness of the silicon-containing material is achieved.